1. Field of the Invention
The present invention relates to a developing cartridge for use in an image forming apparatus such as a copying machine, a facsimile apparatus, or a printer.
2. Description of the Related Art
As a toner cartridge for use in an image forming apparatus such as a copying machine, a facsimile apparatus, or a printer, there has conventionally been proposed a toner cartridge comprising: a toner replenishing port for supplying unused toner to a developing apparatus; an unused toner accommodating portion communicating with the toner replenishing port; a collecting port for collecting waste toner, i.e. left-over toner collected by a cleaner of an image forming apparatus after image transfer process; a waste toner accommodating portion for receiving waste toner, which communicates with the collecting port; and a partitioning wall for parting the unused toner accommodating portion from the waste toner accommodating portion, wherein the unused toner accommodating portion and the waste toner accommodating portion are formed integrally with each other.
However, such a conventional toner cartridge as described above has the following disadvantage. When an amount of waste toner to be collected by the cleaner of the image forming apparatus exceeds the capacity of the waste toner accommodating portion due to occurrence of unexpected usage and environmental conditions, the waste toner accommodating portion is filled to capacity and is thus no longer capable of receiving waste toner.
To solve such a problem, Japanese Unexamined Patent Publication JP-A 4-237079 (1992) discloses a technique embodied as an image forming unit in which an unused toner accommodating portion and a waste toner accommodating portion are formed integrally with each other. In this construction, even if the amount of the collected waste toner exceeds the capacity of the waste toner accommodating portion, the waste toner accommodating portion is protected against damage without the waste toner accommodating portion being increased in size more than necessary. That is, in the partitioning wall located between the unused toner accommodating portion and the waste toner accommodating portion is provided an opening portion having a shutter which opens under the pressure of waste toner to be accommodated in the waste toner accommodating portion. This arrangement causes waste toner in excess of the capacity of the waste toner accommodating portion to flow into the unused toner accommodating portion.
Moreover, Japanese Unexamined Patent Publication JP-R 8-44179 (1996) proposes a toner cartridge which allows effective use of unused toner and effective use of a space of a waste toner accommodating portion. This toner cartridge has such a structure that an unused toner accommodating portion and a waste toner accommodating portion are formed integrally with each other, and is provided with a pair of toner conveying members formed so as to penetrate through a partitioning wall for parting the unused toner accommodating portion from the waste toner accommodating portion.
By the rotation of the toner conveying member, within the unused toner accommodating portion, unused toner is conveyed toward a replenishing port so as to drop into a developing apparatus. This makes possible effective use of unused toner. On the other hand, within the waste toner accommodating portion, waste toner collected from a collecting port formed in the waste toner accommodating portion is conveyed toward the partitioning wall, located away from the immediately below of the collecting port, and is then stored. This makes possible effective use of a space of the waste toner accommodating portion.
However, these prior art techniques have the following disadvantages. The toner cartridge disclosed in JP-A 4-237079 is so designed that waste toner in excess of the capacity of the waste toner accommodating portion is dropped in a free-fall fashion into the unused toner accommodating portion. In this publication, the whereabouts of the opening portion for allowing waste toner to flow into the unused toner accommodating portion is merely described as a position as far away from a developing roller, which is disposed within the developing apparatus, as possible, and no mention is made as to a specific opening portion formation position on the basis of the amount of the waste toner to be produced. Furthermore, in the toner cartridge, the opening/closing action of the shutter disposed in the opening portion is dependent solely upon pressure from waste toner stored in the waste toner accommodating portion. Therefore, in a case where produced waste toner is unexpectedly increased in quantity due to the influence of the usage and environmental conditions, it is impossible to convey the waste toner to the unused toner accommodating portion in accordance with the amount of the waste toner produced, resulting in failure of proper control of the amount of the waste toner stored in the waste toner accommodating portion. That is, it is impossible to control an amount of waste toner to be conveyed from the waste toner accommodating portion to the unused toner accommodating portion.
On the other hand, in the toner cartridge disclosed in JP-A8-44179, the waste toner accommodating portion and the unused toner accommodating portion are formed integrally with each other, and coaxially within each of the toner accommodating portions is disposed conveying means for dispersing toner evenly. However, this construction, though having the technical advantage in that the waste and unused toner accommodating portions have a common conveying means driving source, is not intended for moving waste toner from the waste toner accommodating portion to the unused toner accommodating portion. Therefore, in a case where waste toner is increased in quantity due to the usage condition or other factors, in order for the entire amount of the waste toner produced to be stored in the waste toner accommodating portion without causing damage to the waste toner accommodating portion, the waste toner accommodating portion needs to have an unduly large size.
An object of the invention is to provide a developing cartridge used with one-component and dual-component developer, in which developer can be fed from a transfer residual developer accommodating portion to an unused developer accommodating portion without the transfer residual developer accommodating portion being increased in size more than necessary, and an amount of developer to be moved can be controlled properly. Another object of the invention is to provide an image forming apparatus employing said developing cartridge.
The invention provides a developing cartridge comprising:
a housing including a first accommodating portion for accommodating developer yet to be used in development, and a second accommodating portion for accommodating developer having been used in development, the second accommodating portion being arranged adjacent to the first accommodating portion; and
conveying means having a conveying member, for conveying, when an amount of developer to be stored in the second accommodating portion exceeds a predetermined level, the developer from the second accommodating portion to the first accommodating portion, the conveying means being so formed as to extend over the first and second accommodating portions.
According to the invention, the conveying means having a conveying member is so formed as to extend over the first and second accommodating portions. When an amount of developer to be stored in the second accommodating portion exceeds a predetermined level, the conveying means conveys the developer from the second accommodating portion to the first accommodating portion. In this arrangement, when transfer residual developer collected after image development process is increased in quantity and consequently an amount of developer to be stored in the second accommodating portion exceeds a predetermined level, the developer is conveyed from the second accommodating portion to the first accommodating portion by the conveying member. As a result, the developer stored in the second accommodating portion is decreased in quantity. This eliminates the need to make unnecessarily large the capacity of the second accommodating portion for accommodating transfer residual developer.
In the invention, it is preferable that the conveying member is provided with a conveyance amount adjusting member for adjusting a conveyance amount of developer.
According to the invention, the conveying member is provided with a conveyance amount adjusting member for adjusting a conveyance amount of developer. This allows proper control of an amount of transfer residual developer to be conveyed from the second accommodating portion to the first accommodating portion, thereby preventing transfer residual developer from being fed to the first accommodating portion in excessively large quantities. Thus, even in a case where image development is performed with use of developer mingled with transfer residual developer, degradation in developed image quality can be successfully prevented.
In the invention, it is preferable that the first accommodating portion is provided with a first agitating member for agitating developer, and the conveying member is formed integrally with the first agitating member.
According to the invention, the first accommodating portion is provided with a first agitating member for agitating developer. This allows the unused developer yet to be used in development stored in the first accommodating portion to be evenly dispersed. Moreover, the conveying member and the first agitating member, which are conventionally provided as two separate components, are formed in one piece, and thus can be driven by a single, common driving source. This helps reduce the number of the constituent components, thereby keeping the manufacturing cost at a minimum.
In the invention, it is preferable that the second accommodating portion is provided with a second agitating member for agitating developer, and the conveying member is formed integrally with the second agitating member.
According to the invention, the second accommodating portion is provided with a second agitating member for agitating developer. This allows the transfer residual developer collected in the second accommodating portion to be evenly dispersed, and thereby prevents uneven dispersion. Therefore, it never occurs that the partial buildup of the transfer residual developer collected in the second accommodating portion, which is produced as a result of uneven dispersion, becomes so large in quantity that the developer reaches the conveying member. This makes it possible to prevent occurrence of such a problem that the developer is inadvertently conveyed to the first accommodating portion, though the developer-accommodating capacity of the second accommodating portion is not exceeded.
According to the invention, the conveying member and the second agitating member, which are conventionally provided as two separate components, are formed in one piece, and thus can be driven by a single, common driving source. This helps reduce the number of the constituent components, thereby keeping the manufacturing cost at a minimum.
In the invention, it is preferable that the first accommodating portion is provided with a first agitating member for agitating developer, the second accommodating portion is provided with a second agitating member for agitating developer, and the conveying member is formed integrally with the first and second agitating members.
According to the invention, the conveying member and the first and second agitating members, which are conventionally provided as three separate components, are formed in one piece, and thus can be driven by a single, common driving source. This helps reduce the number of the constituent components, thereby keeping the manufacturing cost at a minimum.
In the invention, it is preferable that the conveying member includes:
a conveying shaft extending in a direction in which the conveying member conveys developer; and
blade members provided in the conveying shaft, the blade members being separated into two sections with respect to a virtual plane including an axis of the conveying shaft, the blade members in one section and the blade members in another section being inclined at a same angle but inclined in mutually different directions, the blade members in the respective sections being spaced.
According to the invention, the blade members, which are disposed in the conveying shaft of the conveying member, are separated into two sections by the virtual plane including the axis of the conveying shaft. Therefore, a die for molding the conveying member can be made structurally simple and thus can be fabricated inexpensively. This leads to reduction in the manufacturing cost.
In the invention, it is preferable that the conveying means further includes: a storage portion constituting a communication path which provides communication between the first and second accommodating portions for storing the conveying member; and a shutter member disposed on an outer circumferential surface of the storage portion. As the conveying shaft rotates about the axis, the blade member slides with the shutter member, and the shutter member is guided by the storage portion to move in a developer conveying direction.
According to the invention, as the conveying shaft of the conveying member rotates about the axis, the blade member disposed in the conveying shaft slides with the shutter member, and thereby the shutter member is guided by the storage portion to move in the developer conveying direction. In this structure, during the time the conveying shaft remains at rest before being rotated, the shutter member covers an opening portion formed in the storage portion, and then, when the conveying shaft starts to rotate, the shutter member is moved to open the opening portion. This helps prevent the unused developer stored in the first accommodating portion from being fed to the second accommodating portion.
In the invention, it is preferable that in the shutter member is formed a projection piece protruding toward an inner part of the storage portion, the projection piece retaining the blade member during the time the conveying shaft remains at rest before being rotated, and being disengaged from the blade member when the conveying member starts to rotate.
According to the invention, by providing a projection piece for the shutter member, the conveying member is inhibited from unnecessary rotation before being initially rotated. As a result, during the transportation and handling of the developing cartridge, the conveying member is inhibited from rotation and therefore the shutter member is no longer allowed to move in the developer conveying direction. Moreover, the opening portion formed in the storage portion can be kept in a closed state, thereby preventing backflow of the developer from the first accommodating portion to the second accommodating portion.
The invention further provides an image forming apparatus comprising:
the said developing cartridge;
a photoconductive body for carrying an electrostatic latent image;
developing means for visualizing the electrostatic latent image carried on the photoconductive body with use of developer supplied from the developing cartridge;
transfer means for transferring developer deposited on the photoconductive body onto a recording paper sheet;
residual developer removing means for removing developer remaining on the photoconductor body after image transfer process; and
collecting means for collecting developer removed by the residual developer removing means.
According to the invention, the image forming apparatus includes one of the said developing cartridges. Thus, miniaturization of the apparatus can be achieved without the second accommodating portion included in the developing cartridge being increased in size more than necessary. Moreover, an amount of transfer residual developer to be conveyed from the second accommodating portion to the first accommodating portion is limited to an amount exceeding a specified capacity of the second accommodating portion. Thus, even in a case where image formation is performed with use of developer mingled with transfer residual developer, degradation in the formed image quality can be successfully prevented.